Delay mercury relay



y 21, 1964 v. HoRowrrz DELAY MERCURY RELAY Filed on. 31, 1961 II'IIIIII INVENTOR Vic-r02 Hozzowrrz IIIIIIII 747712 Ill! rtrlblll. at)! m k. llllllll lllillldllllia ATTORNEYS United States Patent 3,141,940 DELAY MERCURY RELAY Victor Horowitz, Oceanside, N.Y., assignor to Ebert Electronics Corporation, Queens Village, N.Y., a corporation of New York Filed Get. 31, 1961, Ser. No. 149,025 7 Claims. (Cl. 200-412) This invention relates to mercury relays of the displacer type wherein a mass of mercury is displaced in order to provide contact between two spaced electrodes, and more particularly to a mercury relay having two mercury displacing elements therein and which move in unison on one cycle of operation to provide a delayed making of contact between the electrodes, and which move relatively to each other on another cycle of operation in order to provide immediate breaking of contact between said electrodes.

One of the disadvantages in the prior art of designing mercury relays having delayed make or break functions is that complicated structure involving the use of interrlated gas and/or mercury metering orifices and/ or linkage were required during the action of the displacement of the mercury. In other prior art systems the use of a compressible gas which was displaced by the displaced mercury added to the problems of metering. Consequently, in the design of mercury relays having both the displaceable mass of mercury and a displaceable mass of gas, accurate and non-clogging metering devices were necessary to insure consistency of operation over a long period of time. As a result of the increased number of components introduced in mercury relays in order to achieve accurate delay functions, such relays are susceptible to many different variables in the operation thereof which may cause inconsistency of operation. For example, in mercury relays using a compressible gas which is to be metered, a change in the surrounding pressure and/ or temperature will have an effect of changing the delay characteristic of the mercury relay.

In addition to the foregoing disadvantages, prior systems in many cases have required the use of energizing coils of high current capacity in order to overcome friction introduced in the mercury relay due to the weight and resistance of the moving elements therein. In these cases, since high coil count was required, the shell or container containing the mercury to be displaced often became heated thus causing a change in the operating characteristics of the mercury relay. In addition, eddy currents set up in the relay due to the influence of electromagnetic field on magnetic materials therein increased the design problems and added to inconsistent operation.

These and other disadvantages are overcome according to the present invention by providing in a container having a pool of mercury therein and two spaced electrodes mounted to extend thereinto, two relatively movable mercury displacing elements each having a different rate of displacement. Surrounding a part of the container is an energizing coil. Inside the container, one of the moving elements is a tubular armature which is actuatable by said coil. The armature rides on the inside surface of the container and has a normal position of buoyancy in the pool of mercury therein. The other movable element rides on the inner surface of the container and has an orifice at the lower end thereof. Either or both of the movable elements of the container may have frictional engaging surfaces with container studs made of material having a very low coefficient of fric tion. The spaced electrodes inside of the container are located so that when the coils are not'energized, the level of the pool of mercury is some distance below said electrodes. When the coil is energized, the armature element exerts a downward force against the orificed element,

3,141,940 I Patented July 21, 1964 thereby causing both elements to move in unison into the pool of mercury, thereby displacing the pool of mercury. However, the rate of movement of the two elements moving in unison is limited by the size of the orifice in the orifice element. This limiting of the downward movement to displace the mercury in the container by the orifice produces the delay in the making of contact between the two spaced electrodes due to the pool of mercury reaching a sufiicient level to establish contact therebetween.

When the coil is subsequently tie-energized, the natural buoyancy of the armature element causes it to rapidly rise in the pool of mercury. The rising of the armature element rapidly displaces the mercury downward in the container, thereby rapidly breaking electrical contact between the two spaced electrodes. Although the orificed element returns to its natural buoyant position in the pool of mercury at a slower rate than the armature element, the displacement of the armature element alone is sufficient to displace an amount of mercury to rapidly break the contact between the two spaced electrodes.

It is, accordingly, an object of this invention to provide a mercury relay of the delayed make, immediate break type and having a minimum of movable parts therein in order to insure consistent operation over a long period of time.

It is another object of this invention to provide a mercury relay having two relatively movable mercury displacing elements therein, one of which controls the rapidity of a making of contact, and the other of which controls the rapidlity of a breaking of contact between two spaced electrodes in said container.

Another object of this invention is to provide a mercury relay having low frictional resistance among the various moving elements thereof by providing self lubrieating parts, and having minimum susceptibility to electromagnetic field effects and to temperature change effects.

These and other objects and features of the invention will be better understood by referring to the accompanying drawings, in which like reference numerals are used to indicate like part, and in which:

FIGURE 1 is a longitudinal cross sectional view of an embodiment of the invention;

FIGURE 2 is a modified cross sectional view of an embodiment of the invention;

FIGURE 3 is another cross sectional view of an em bodiment of the invention, and

FIGURE 4 is a cross sectional view showing a modification of the embodiment of FIGURE 3.

Referring to FIGURE 1, a mercury relay according to the invention is shown generally at 10 having a container 12 which may be made of glass, metal or hard plastic. The material for the container 12 is preferably of material which is chemically, electrically and electromagnetically inert, and which has self-lubricative properties. As an example, the container 12 may be comprised of nylon, Delrin, or nylon filled with fiberglass. Inside of container 12 is a pool of mercury 14 having a level indicated at 16. Surrounding the container 12 is an electromagnetic coil 18. A mercury displacing orificed member 20 is positioned in the container and is bouyant in the mercury pool 14. The mercury displacing member 20 has an orifice 22 at the bottom thereof through which the mercury 14 may pass. The movable member 20 is of chemically, electrically and electromagnetically inert material, preferably a ceramic. The member 26 has mounted on the outside periphery thereof studs 22 which engage the inside surface of the container 12 for sliding frictional engagement therewith. The studs are preferably of self-lubricating material having low coefiicient of friction such as for example, nylon or Delrin, or a metal. The studs 22 permit the orificed member 20 to slide up and down in snare-ac the container 12 without lateral displacement of the member 20 therein.

Loosely fitted inside of the orificed member 20 is an armature member 26 which is in the form of a tube. The mside portion of the armature member 26 is preferably of a ceramic material having properties of chemical, electrical and electromagnetic inertness. The inside portion of ceramic material is indicated at 28. The outside portion of armature member 26 is of magnetically permeable metal and actuatable for movement by the electromagnetic coils 18 when energized. The metal portion of the armature member is indicated at 39. The armature member 26 and the orificed member 28 are movable relative to each other.

Output leads 32 and 34 shown at the top of container 12 are sealed with the container 12 so that in addition to the pool of mercury 14 contained in container 12, there is either an inert gas or a vacuum hermetically sealed therein. The leads of output conductors 32 and 34 are mounted in the container 12 to form spaced electrodes indicated at 36 and 38. The spaced electrodes 36 and 38 extend into the container for a distance such that when the armature member 26 and the orificed member 20 are not energized by the coil 18, there is a space between the ends of the electrodes 36 and 38 and the level 16 of the mercury pool 14. A cushioning spring 48 is attached to the bottom of the orificed member 28, and another cushioning spring 42 is attached to the armature member 26 in order to protectively cu hion the members 26 and 28 at their furthermost limits of travel in the container 12.

In the operation of the invention as embodied in FIG- URE 1, upon suitable energization of the coil 18, the armature member 26 is attracted downwardly in the container 12 to a central area relative to coil 18. The armature member 26 exerts a force on the orifice member 20 thereby pushing the member 20 with it downwardly into the container. However, due to the restriction of flow of mercury through the orifice 22 of the orificed member 20, the downward progress of the armature 26 and the orificed member 20, moving in unison is delayed. The size of the orifice 22 determines the speed of the downward progress of the orificed member 20 when pushed by the armature member 26, and thereby determines the amount of delay desired in the relay.

When the armature member 26 has reached its position of equilibrium with respect to the coil 18, a certain amount of the mercury pool 14 having been dis placed upwardly in the container due to the displacement of both of the members 26 and 20, the spaced electrodes 36 and 38 are bridged by the mercury 14 to form an electrical contact therebetween. Both the members 28 and 26 are bouyant in the pool of mercury 14. Thus, when the coil 18 is de-energized, the tubular armature member 26 immediately rises to its former bouyant position in the container 12, thereby causing the level 16 of the mercury to return to the vicinity of its original position in the container. The rapid movement of the tubular armature 26 thereby upwardly in the container 12 thereby immediately breaks the electrical conduction path between the spaced electrodes 36 and 38. The orificed member 20 moves upwardly in the container upon de-energization of the coil 18 at a slower rate than the armature member 26. However, the slow return of the orificed member 20 has no effect upon the immediate breaking of the electrical contact between the electrodes since the tubular armature member is of sufficient displacement to lower the level 16 of the mercury 14 to break the electrical contact between the spaced electrodes 36 and 38. The electromagnetic coil 18 may be energized by any suitable source of alternating or direct current.

Referring now to FIGURE 2 which is an embodiment of the mercury relay shown in FIGURE 1, therein is shown a mercury relay wherein the outward conductors are located at opposite ends of the container. A container 44 constructed of the same material as the container of FIGURE 1 has sealed into the opposite ends thereof conductors 46 and 48 respectively. Conductor 46 is sealed into the container so that an insulated portion thereof indicated at 58 extends into the container. An electrode 52 of the conductor 46 is fastened or suitably bonded or welded to a cup indicated at 54 of suitable insulating material such as alumina. The open end of cup 54- faces upward in the container 44. The bare electrode 52 of the conductive lead 56 is located inside of the cup 54 for electrical contact with the pool of mercury in the container. The pool of mercury is indicated at 56 and has a normal level indicated at 58 as generally below the level of the top of cup 54. Surrounding the container is an electromagnetic coil indicated at 60 energizable by a suitable source of alternating or direct current.

Movably mounted in the container 44 and operative in exactly the same manner as shown in conjunction with FIGURE 1 are the armature member 26 and the orificed member 28. Cushioning springs 4-8 and 42 connected respectively to the orificed member and to the armature member also operate in exactly the same manner as that described in conjunction with FIGURE 1.

In the operation of the embodiment shown in FIGURE 2, when the coil 68 is suitably energized, the armature member 26 is attracted downwardly in the container 44 thereby exerting a downward pushing force against the orificed member 28 in the same manner as described in conjunction with FIGURE 1. The movement of the members 28 and 26 downwardly in unison displaces a mass of the mercury 56 upwardly as the armature member descends. As the two members 28 and 26 moving in unison downwardly displace the mercury, the level of the mercury 58 travels past the open end of the cup 54 and thereby filling the cup with mercury and establishing an electrical conduction path through the mercury between the electrodes 52 and the electrodes 48.

When the coil 60 is de-energized, the armature member 26 due to its natural buoyancy in the mercury pool 56 rises rapidly in the container to displace a sufiicient amount of mercury so that electrical contact between the electrode 52 and the electrode 48 is broken. The fact that some mercury may remain inside the cup 54 is of no consequence since the cup itself is an insulating member and therefore no contact will be existing between the pool of mercury at a lower level and the mercury inside of the cup 54. In order to vary the delay of the make cycle of the relay, as shown in the embodiment of FIG- URE 1, the size of the orifice 22 may be varied to give the desired delay characteristic.

Reference is now made to FIGURE 3 in which is shown another embodiment of the invention. In the embodiment of FIGURE 3, instead of the armature member being positioned for movement inside of the confines of the orificed member, each of the respective members are constructed to be of such size so that they are each in sliding engagement with the inner walls of the container. This permits more economical operation especially in that the size of the members may be reduced, and the weight of the armature member may be reduced. In that the embodiment of FIGURE 3 shows the spaced electrodes in the container oriented in the same manner as that of FIGURE 1 and all of the other parts of the relay located to operate in the same manner as shown in FIG- URE l, the same reference numerals will be used therein to denote the various similar parts except those of the movable orificed and armature members in the container. Instead of the movable armature member 26 being positioned inside of the orificed member 20 as shown in FIG- URE 1, an orifice member 62 is shown having the orifice at the top of the dome form of the orifice member structure. The orifice member 62 rides in self-lubricative sliding engagement with the inside of the walls of container 12 via self-lubricating stud members 64. The studs 64 are made of such material, for example, nylon or Delrin, that the orificed member 62 slides easily and with low frictional resistance on the inside walls of the container 12.

An armature member is shown at 66 and has the same radial dimensions as the orificed member 62. The armature member 66 is a tube the lower end of which is engageable with the top surface of the orificed member 62. Armature member 66 rides on the inside walls of container 12 via self-lubricating studs 68 which are of the same design and material as those of studs 64. The level 16 of the pool of mercury 14 is located in the container 12 so that the normal level of 16 of the mercury is at a distance below the ends of the electrodes 36 and 38.

The principle of operation of the embodiment of FIG- URE 3 is the same as that of FIGURE 1 except for the interaction of the orificed and armature members 62 and 66 respectively. Upon energization of the coil 18, the armature member 66 is attracted to an equilibrium position in the container against the buoyant force of the mercury 14. The downward force of the armature member 66 is exerted against the orificed member 62 and in ac cordance with the size of the orifice 22, the movement of members 62 and 66 downwardly to displace the pool of mercury 14 upwardly is delayed. The members 62 and 66 move in unison downwardly and the level 16 of the mercury rises until the mercury bridges the spaced electrodes 36 and 38 thereby establishing electrical contact therebetweeen.

Upon de-energization of the electromagnetic coil 18, the natural buoyancy of the armature member 66 causes said member to rise rapidly in the pool of mercury until it returns to its normal position of buoyant equilibrium therein. The rapid displacement of the armature member 66 in the pool of mercury is sufiicient to cause the level 16 of the mercury to drop immediately, thereby breaking the electrical contact between the spaced electrodes 36 and 38.

The arrangement of the movable members as shown in FIGURE 3 to displace the mercury may be used in the mercury relay wherein the electrodes are located on opposite ends of the container. This is shown in FIGURE 4 wherein the same reference numerals as those of FIG- URE 2 are used to denote the various parts of the mercury relay of the type having the electrodes at opposite ends thereof. In the mercury relay of FIGURE 4, the cup 54 is shown located at a sufficient distance above the level 58 of the mercury so that upon energization of the coil 60, the armature member 66 presses downward against the buoyant force of both members 66 and 68 so that a sufficient mass of mercury is displaced to established electrical contact between the electrode 52 and the electrode 48.

In accordance with the invention the electrodes may be sealed to the container with epoxy, epoxy resins being known for having the property of being bondable with dissimilar type surfaces or materials such as for example metal-to-glass seals or plastic composition to metal or glass seals. The container may be made my material such as nylon filled with fiberglass, said material having the property of being an insulator, non-shattering, self-lubricating, and non-corrosive. The studs such as enumerated at 24, 68, 64 may also be of self-lubricating material such as previously pointed out. The self-lubricating properties of the various interacting moving parts permits the relay according to the invention to be operable with a minimum of friction, thus insuring consistency of operation over a long period of time and reducing the current requirements of the energizing coils, thereby reducing thermal and eddy current effects.

From the foregoing the advantages of the present invention become apparent when it is realized that the arrangement of the present invention provides a mercury relay of consistent operating characteristics and with a minimum of interacting parts thereby insuring a maximum reliability over a maximum length of time. Due to the low frictional resistance among the interacting moving parts, the strength of the electromagnetic coils may be held to a minimum, thus eliminating undesirable heating of the mercury relay. In addition, the inertness of the materials used for the orificed members and for the armature member as shown in FIGURES 1 and 2 permits consistent operation over long period of time because these said members will not develop any electrical or electromagnetic properties to change the operating characteristics of the relay of the invention.

Instead of using an orificed member having an orifice therein which when manufactured is, of course, of a constant size, a stainless steel plug insertable into a standard orifice as, for example, by screw thread arrangement, may be alternatively provided. Such an arrangement permits the production of screw stainless steel threaded inserts having different size orifices therein into ceramic members having standard size orifices to receive the threaded stainless steel screw plug. This procedure permits the ceramic orifice members to be mass produced out of the same mould thus lending great economy to the production of mercury relays according to the invention. Instead of using threaded screw members having orifices therein, other insertable elements into a standard orifice of a movable member in a relay will suggest themselves to those skilled in the art.

It will be understood that the embodiments of the invention as shown in FIGURES 1 through 4 are merely illustrative examples of the invention, and modifications and expedience thereof will occur to those skilled in the art, it therefore being understood that the scope of the invention is limited only by the following appended claims.

What is claimed is:

l. A mercury relay of the displacer type to produce a delayed make and immediate break of electrical contact, comprising a pool of mercury, a container for said pool of mercury, an orificed non-magnetic element buoyant in said pool of mercury, a buoyant unmetered magnetic armature element resting on but unattached to said orificed element, an electromagnetic energizing coil surrounding a portion of said container and energizable to urge said armature element downwardly into said pool of mercury and in downwardly actuating relation to said orificed element, and a pair of spaced electrodes located in said container between which electrical contact occurs when said pool of mercury is displaced by said elements and breaks when said magnetic armature element alone rises.

2. Apparatus according to claim 1, including insulating means surrounding one of said electrodes, said one of said electrodes being located above the level of the pool of mercury when the coil is de-energized, and said one of said electrodes having a bare portion surrounded by an insulative cup spaced therefrom and arranged to be filled by the mercury when displaced.

3. A mercury relay of the displacer type to produce a delayed make and immediate break of electrical contact comprising a pool of mercury, a container for said pool of mercury, an orificed element buoyant in said pool of mercury, a buoyant armature element resting on said orificed element, an electromagnetic energizing coil surrounding a portion of said container and energizable to urge said armature element against said orificed element, and a pair of spaced electrodes located in said container between which electrical contact occurs when said pool of mercury is displaced by said elements, wherein said orificed element is in the shape of an inverted dome and said armature element is in the form of a tube having an outer portion of magnetic material and inner portion of insulating material, the armature element being freely movable up and down inside of said orificed element.

4. A mercury relay of the displacer type to produce a delayed make and immediate break of electrical contact comprising a pool of mercury, a container for said pool of mercury, an orificed element buoyant in said pool of mercury, a buoyant armature element resting on said orificed element, an electromagnetic energizing coil surrounding a portion of said container and energizable to urge said armature element against said orificed element, a pair of spaced electrodes located in said container between which electrical contact occurs when said pool of mercury is displaced by said elements wherein said orificed element is in the shape of an inverted dome and said armature element is in the form of a tube having an outer portion of magnetic material and inner portion of insulating material, the armature element being freely movable up and down inside of said orificed element, and including studs comprised of self-lubricative material mounted on said orificed element for sliding engagement with the inside surface of said container.

5. Apparatus according to claim 1, wherein said orificed element is in the shape of a dome having an orifice therein and said armature element is in the form of a tube, both of said elements having self lubricative studs mounted thereon for sliding engagement with the inside surface of said container.

6. A mercury relay of the displacer type, comprising a pool of mercury, a pair of contacts, at least one of said contacts being isolated from said pool of mercury when said pool of mercury is at a lower level and said contacts being bridged by said mercury when said pool of mercury is at a predetermined higher level, a first buoyant nonmagnetic mercury displacer having a metering orifice for said mercury, a second magnetic buoyant mercury displacer having provision for unmetered flow of said mercury on movement of said second displacer, said second displacer and said first displacer being mutually unattached but normally in physical contact, an actuating coil for said second displacer, said second displacer being movable in a first sense in response to energization of said coil and in an opposite sense in response to de-energization of said coil, said first displacer being movable in response to movement of said second displacer when said second displacer moves in one of said senses, and being free of said second displacer when said second displacer moves in the other of said senses, whereby metering of said mercury occurs only during movement of said second displacer in one of said senses.

7. A delayed make rapid break mercury relay of the mercury displacer type, comprising an envelope, a pool of mercury in said envelope, a magnetic mercury displacer buoyant in said mercury and located in said envelope, a coil surrounding said envelope and arranged for actuating said magnetic mercury displacer into mercury displacing position in response to energization of said coil, and a buoyant orificed metering device unattached to said magnetic mercury displacer and located thereunder in said pool in contact with said magnetic mercury plunger.

References Cited in the file of this patent UNITED STATES PATENTS 1,915,462 Zuckschwerdt June 27, 1933 2,060,811 Larson Nov. 17, 1936 2,367,498 Hedin Ian. 16, 1945 2,457,681 Keating et al Dec. 28, 1948 

1. A MERCURY RELAY TO THE DISPLACER TYPE TO PRODUCE A DELAYED MAKE AND IMMEDIATE BREAK OF ELECTRICAL CONTACT, COMPRISING A POOL OF MERCURY, A CONTAINER FOR SAID POOL OF MERCURY, AN ORIFICED NON-MAGNETIC ELEMENT BUOYANT IN SAID POOL OF MERCURY, A BUOYANT UNMETERED MAGNETIC ARMATURE ELEMENT RESTING ON BUT UNATTACHED TO SAID ORIFICED ELEMENT, AN ELECTROMAGNETIC ENERGIZING COIL SURROUNDING A PORTION OF SAID CONTAINER AND ENERGIZABLE TO URGE SAID ARMATURE ELEMENT DOWNWARDLY INTO SAID POOL OF MERCURY AND IN DOWNWARDLY ACTUATING RELATION TO SAID ORIFICED ELEMENT, AND A PAIR OF SPACED ELECTRODES LOCATED IN SAID CON- 